1. Field of the Invention
The present invention relates generally to woodworking equipment. More particularly, this invention relates to a profiled cutter or coping apparatus and method of operation.
2. Description of Related Art
Molding used in the construction of residential and commercial properties provides a decorative finish to ceiling/wall interfaces, floor/wall interfaces and along walls at table or chair height in rooms. Molding may have a plain finish with a straight profile or it may be decoratively shaped with an elaborate profile using a machine for forming the profile, e.g., a shaper, a router or a molder.
Where two strips of molding join at an internal 90° angle, e.g., where two walls intersect, there are a couple of methods of joining the intersecting strips of molding. The first method is by forming a miter joint, i.e., at 45° angles, so that the respective patterns match together when joined at the 90° wall intersection. Miter joints work well for picture frames and also for external 90° wall intersections because when nailed or screwed together the miter joint is driven together. However, miter joints are not preferred for joining molding at internal 90° wall intersections. This is because when both sections of molding are nailed or screwed to the wall the miter joint tends to separate with each piece of molding moving toward the wall rather than toward the adjoining section of molding as the sections are affixed to the wall by nails or screws, leaving an unsightly gap.
The other conventional method of joining molding at an internal corner is to form a coped butt joint. Where the molding has a plain or straight profile, the sections of molding to be joined are merely cut on a 90° angle, with the first section affixed to its associated wall having its end resting against the adjoining wall. The second section is affixed to its associated wall and its end resting against the other section of molding. However, when the molding is profiled, it has been traditionally necessary to use a coping saw to properly hand cut the selected profile along the end of the second section of molding so that it will buff against the oppositely profiled first section of molding.
Those skilled in the art know that the formation of a coped butt joint using a coping saw for an ornate molding profile is a tedious and imprecise process of hand-cutting the end of the second section of molding. Even a skilled craftsman may find it difficult to precisely follow a template or profiled line with a coping saw to form the perfectly coped butt joint.
Various approaches to automating the coping process have been suggested in art. Some of the automated coping saws of the prior art are of the reciprocating blade variety. For example, see, U.S. Pat. No. 6,550,365 to Zhang et al. and U.S. Pat. No. 5,027,518 to Adomatis. In contrast, several of the automated coping saws of the prior art are of the endless blade variety. For example, see, U.S. Pat. No. 5,388,334 to Halsey, U.S. Pat. No. 6,736,037 and U.S. Patent Publication No. 2004/0211304, both to Dean. While these conventional coping saws all employ various means for powering the blade, thus, easing the effort required by the user to cope a piece of molding, they all still appear to require significant user skill in following a given pattern necessary to make an accurately coped butt joint. An additional drawback with the conventional automated coping saws is that coping many pieces of wood with a given pattern requires the user to follow a pattern for each cut. Thus, the lack of repeatability is a significant drawback of the conventional automated coping saws.
One type of device used to repeatedly cut thick objects, such as a stack of paper, is the hydraulic paper cutter. Examples of conventional hydraulic paper cutters may be found in U.S. Pat. No. 3,452,630 to Malm and U.S. Pat. No. 4,019,416 to Krause. Such hydraulic paper cutters employ shearing blades that cut stacks of paper along straight lines. However, such devices are unsuitable for coping a piece of wood because the required molding pattern is never a straight line. Hydraulic paper cutters are only capable of cutting a straight line and not a curved pattern. Hydraulic paper cutters are also not capable of cutting arbitrary coping patterns. Furthermore, the characteristics of a stack of paper are very different from a strip of molded wood under shearing conditions. For example, a strip of wood molding may have at least one surface that is not flat and thus could not be efficiently held down by hydraulic paper cutter shoes. Additionally, a strip of wood molding may inelastically compress and/or splinter when sheared, unlike a stack of paper.
For all of the above reasons, it would be desirable to have a more efficient automated method of forming coped butt joints that is repeatable and less subject to human error. Accordingly, there exists a need in the art for a coping apparatus and method of operation that automates the process of forming coped butt joints in strips of molding for internal wall angles typically about a 90° angle that alleviates the problems associated with the use of miter joints or the time consuming use of a coping saw.